| 2022-01-18 |
hst_0974.pmap |
operational |
Lack of DESCRIP column in table led to non-standard characters being printed during pipeline processing, which broke some step of data ingest in DMS. New SPOTTAB has DESCRIP and PEDIGREE columns, like other reference tables, and this appears to fix the problem. |
| 2022-01-11 |
hst_0973.pmap |
archived |
The ACS WFC bias, dark, CTE dark, and sink files were generated following the ACS WFC anneal on Jan 07, 2022, and should be used to calibrate ACS WFC observations taken between Dec 07, 2021 and Jan 07, 2022. |
| 2021-12-10 |
hst_0972.pmap |
archived |
Intrinsic excess thermal energy trapped in the silicon lattice of the WFC3 UVIS detector, known as dark current, is typically removed from science observations using UVIS dark calibration reference files. This dark current can be used as a means to characterize a pixels behavior and determine whether the pixel varies excessively over time compared to its expected noise. We use a novel data structure known as a pixel history image to efficiently evaluate each WFC3 UVIS pixel over time. We find that the vast majority of hot pixels, about 8 percent of the detector in 2021, are in fact quite stable and as such, can be calibrated. A small portion of pixels, less than 1.5 percent, are genuinely unstable and should not be used. To encode this distinction in the UVIS bad pixel reference files, we employ a data quality flag, 32, to mark the unstable pixels identified in this study. Hot pixels continue to be assigned the usual data quality flag, 16. With the additional data quality flag, WFC3 UVIS users will have enhanced control over which pixels to include or exclude during their analyses.
This new bad pixel table was generated using data taken from October 6th, 2021 through October 23rd, 2021. Currently, the Calibration Reference Data System only has WFC3 UVIS bad pixel reference tables up to a USEAFTER date of September 9th, 2021. The automated pipeline should now use these reference files as the bad pixel table on any UVIS datasets obtained between the dates above, or beyond because they represent the most accurate measure of pixel stability at the time of the science observation. These WFC3 UVIS bpx files were generated using 900 second dark exposures from the HST Cycle 28 daily monitoring programs 16414 and 16396. More information about the UVIS bad pixel tables is outlined in the WFC3 ISR 2018.15 and WFC3 ISR 2021.14. |
| 2021-12-09 |
hst_0971.pmap |
archived |
The ACS WFC bias, dark, CTE dark, and sink files were generated following the ACS WFC anneal on Dec 07, 2021, and should be used to calibrate ACS WFC observations taken between Nov 10, 2021 and Dec 07, 2021. |